Method for the fabrication of a screw member for plate member fastener

ABSTRACT

A method for making a screw member for plate member fastener is disclosed to include the step of preparing a metal element subject to a predetermined size and then processing the metal element through a cold extrusion forging operation to form a head at one end, a connection portion at an opposite end and a shank between the head and the connection portion, the step of processing the connection portion through a thread rolling operation to form threads around the periphery, the step of processing the threads to form a stop end edge at one side in proximity to the shank, and the step of finishing the final product.

BACKGROUND OF THE INVENTION

1. Field of the Invention:

The present invention relates to a plate member fastener fabricationmethod and more particularly, to a method for making a screw member forplate member fastener that raises reliability of the use of the platemember fastener.

2. Description of the Related Art:

When fastening plate members together, a positioning screw formed of aknob, a ring and a screw nail is usually used. During installation, thescrew nail and the ring are secured to the first plate member, and thenthe knob is rotated to drive the screw nail into the second platemember, and then a hand tool is used to fasten tight the screw nail,affixing the first and second plate members together. This plate memberjoining method can be used in a machine tool to join plate memberstogether.

The power drive or speed-adjustment unit of a machine tool is providedinside the housing. To facilitate repair of the machine tool oradjustment of the output speed of the machine tool, a detachable platemember is usually provided at the housing of the power drive orspeed-adjustment unit. Screw bolts are commonly used to fasten themovable plate member to the housing. When unfastening screw bolts todismount a movable plate member from the housing, the associating locknuts may fall from the screw bolts.

There is known a plate member fastener comprised of a cap, a screwmember, a spring member and a locating base for joining two metal platemembers together. After fixation of the locating base of the platemember fastener to a through hole on a first plate member, the screwmember is threaded into a screw hole on a second plate member to securethe first plate member and the second plate member together. Because thelocating base of the plate member fastener is kept secured to the firstplate member after removal of the first plate member from the secondplate member, the plate member fastener will not be missed by accident.According to this design, the screw member A, as shown in FIG. 9, has ahead A1, a shank A2 perpendicularly extended from the center of thebottom side of the head A1 and a connection portion A3 axially extendedfrom the bottom end of the shank A2 remote from the head A1. Theconnection portion A3 has an outer thread A31 spirally extending aroundthe periphery. The outer thread A31 has a reduced end portion A311.During installation, the outer thread A31 of the connection portion A3is threaded into the screw hole on the second metal plate member (notshown). When the reduced end portion A311 of the outer thread A31reaches the inner thread of the screw hole of the second metal platemember, the first metal plate member and the second metal plate memberare firmly secured together. If the operator continuously rotates thehead A1 of the screw member A at this time, the reduced end portion A311of the outer thread A31 will be threaded into the screw hole of thesecond metal plate member, causing the screw member A to be stuck in thescrew hole of the second metal plate member. Therefore, when threadingthe screw member A into the screw hole of the second metal plate member,the rotary driving force must be properly controlled to avoidoverthreading.

Further, the reduced end portion A311 of the outer thread A31 slopes inone direction. When the spring member is sleeved onto the screw member Aand stopped between the reduced end portion A311 of the outer thread A31and the bottom side of the head A1, the spring member may bias. When thescrew member A, the cap and the locating base are assembled, the cap andthe locating base may be not kept in perfect alignment. Small deviationof the component parts may increase the difficulty of the installationof the plate member fastener.

Accordingly, there is a strong need for plate member fastener thatovercomes the aforementioned and other deleterious effects of the priorart plate member fastener.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances inview. It is therefore the main object of the present invention toprovide a method for the fabrication of a screw member for plate memberfastener, which facilitates mounting and dismounting of the plate memberfastener, avoiding overthreading during installation.

A screw member fabrication method in accordance with the presentinvention includes the steps of (a) preparing a metal element subject toa predetermined size, and then processing the metal element through acold extrusion forging operation to form a head at one end, a connectionportion at an opposite end and a shank between said head and saidconnection portion, (b) processing the connection portion through athread rolling operation to form threads around the periphery of theconnection portion, (c) processing threads to form a stop end edge atone side in proximity to the shank, and (d) finishing the final product.When the screw member is used in a plate member fastener and threadedthrough a mounting through hole on a first metal plate member into acorresponding screw hole of a second metal plate member to secure thefirst metal plate member and the second metal plate member together, thestop end edge of the screw member avoids overthreading, preventingsticking of the screw member in the second metal plate member.

Further, the stop end edge is a flat edge extending in directionperpendicular to the axis of the screw member. When the screw member isused in a plate member fastener and a spring member is sleeved onto thescrew member and stopped between the bottom side of the head and stopend edge of the screw member, the screw member will not be forced tobias and can be accurately threaded into the screw hole of the secondmetal plate member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of the plate member fastener in accordancewith the present invention.

FIG. 2 is a flow chart of the present invention showing the fabricationof a screw member for plate member fastener in accordance with thepresent invention.

FIG. 3 is a schematic sectional view, showing a metal element set inforging dies of a forging machine according to the present invention.

FIG. 4 is a schematic sectional view of the present invention, showingthe thread rolling operation (I).

FIG. 5 is a schematic sectional view of the present invention, showingthe thread rolling operation (II).

FIG. 6 is side view of a finished screw member according to the presentinvention.

FIG. 7 is an exploded view in sectional elevation of the presentinvention, showing the cap molded on the head of the screw member.

FIG. 8 is a sectional view of the present invention, showing the platemember fastener fastened to two metal plate members.

FIG. 9 is a side view of a screw member for plate member fasteneraccording to the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 7, a plate member fastener in accordance withthe present invention comprises a cap 1, a screw member 2, a barrel 3,and a spring member 4.

The cap 1 is a hollow member having a center opening 10 axiallyextending through the top and bottom sides for receiving the barrel 3,the screw member 2 and the spring member 4, a serrated inside retainingportion 11 arranged around the inside wall near the top side forretaining the engagement portion 211 of the screw member 2, and a grip12 located on the periphery at the top side for gripping by hand.

The screw member 2 is a metal member having a head 21, an engagementportion 211 formed on the periphery of the head 21 for engagement withthe serrated inside retaining portion 11 of the cap 1, a shank 22perpendicularly extended from the center of the bottom wall of the head21 and terminating in a connection tip 23, threads 231 spirally arrangedaround the periphery of the connection tip 23 and defining a stop endedge 2311 at a proximal side relative to the shank 22, and a tool groove24 located on the top wall of the head 21. Further, the tool groove 24can be a Phillipes groove, keystone groove, asterisk groove or hexgroove.

The barrel 3 is a hollow cylindrical metal member having an insideaccommodation space 30 extending through top and bottom sides thereof, astep 31 located on the inside around the inside accommodation space 30,a locating groove 32 extending around the inside wall inside the insideaccommodation space 30 and abutted against the bottom side of the step31, a bottom extension tube 33 axially forwardly extended from thebottom side of the barrel 3, and a bonding edge 331 defined on thebottom side of the barrel 3 around the bottom extension tube 33.Further, a retainer ring 34 is secured to the periphery of the shank 22of the screw member 2 and positioned in the locating groove 32 insidethe inside accommodation space 30.

The spring member 4 is sleeved onto the screw member 2, having adeformable coiled body 41 surrounding the shank 22 of the screw member 2and two end portions 42 respective disposed at the two distal ends ofthe deformable coiled body 41.

Referring to FIGS. 2,3 4, 5 and 6, the screw member 2 is made of a metalelement 5 that can be a steel, iron or stainless steel ingot.

The screw member 2 is made subject to the following steps:

-   100 Prepare a metal element 5 subject to a predetermined size.-   101 Process the metal element 5 through a cold extrusion forging    operation to form the desired head 21, shank 22 and connection    portion 23.-   102 Process the connection portion 23 through a thread rolling    operation to form the desired threads 231.-   103 Process the threads 231 to form the desired stop edge 2311 at    one side in proximity to the shank 22.-   104 Finish the desired screw member 2.

The metal element 5 is extruded into the desired length and widththrough a cold extrusion operation, and then processed through a coldforging process to form the desired head 21, shank 22 and connectionportion 23. The cold extrusion forging operation is describedhereinafter. After extrusion through a cold extrusion operation, themetal element 5 is put in between an upper die 61 and a bottom die 62 ofa forging machine 6, and then forged to form the desired shank 22 andconnection portion 23, and then a hammer forging die 63 is attached toone end of the metal element 5 outside the upper die 61 and the bottomdie 62 and hammered to forge the respective end of the metal element 5into the desired head 21. Thereafter, the shape-formed metal element 5thus obtained is put in between the thread rolling faces 7111 and 7121of the two flat thread rolling dies 711 and 712 of a first threadrolling die set 71 of a thread rolling machine 7, and then the two flatthread rolling dies 711 and 712 are reciprocated relative to each otherto force the respective thread rolling faces 7111 and 7121 against theconnection portion 23, thereby forming a semi-finished screw member 2having the desired threads 231 around the periphery of the connectionportion 23. Thereafter, the semi-finished screw member 2 thus obtainedis put in between the thread rolling faces 7211 and 7221 of the two flatthread rolling dies 721 and 722 of a second thread rolling die set 72 ofthe thread rolling machine 7 wherein one flat thread rolling dies 721has a top mounting groove 7213 located on the top wall 7210 thereof andan end edge-forming block 7212 affixed to the top mounting groove 7213with a flat end edge-forming face 7214 thereof suspending in the threadrolling face 7211, and then the two flat thread rolling dies 721 and 722of the second thread rolling die set 72 are reciprocated relative toeach other to force the respective thread rolling faces 7211 and 7221against the connection portion 23, causing the flat end edge-formingface 7214 to cut the end portion 2311 of the last thread 231 of thesemi-finished screw member 2 so that a finished screw member 2 havingthe desired stop end edge 2311 at the end of the set of threads 231 inproximity to the shank 22 is thus obtained. When the screw member 2 isthreaded into the screw hole 821 of a second metal plate member 82during the use of the plate member fastener to secure a first metalplate member 81 to the second metal plate member 82, the stop end edge2311 will be stopped against the inner threads 8211 to prohibit forwardrotation, avoiding overthreading of the screw member 2 (see FIG. 8).Further, the flat end edge-forming face 7214 may be directly formedintegral with the thread rolling face 7211 of the flat thread rollingdie 721, or the end edge-forming block 7212 may be separately made andthen inserted into the flat thread rolling die 721.

Referring to FIG. 7, the screw member 2 made subject to the aforesaidfabrication method is fastened to the cap 1, and then the spring member4 is sleeved onto the screw member 2, and then the retainer ring 34 isfastened to the screw member 2 to secure the barrel 3 to the screwmember 2 in the cap 1.

Further, the cap 1 can be directly molded on the head 21 of the screwmember 2 with over-molding technology. After molding, the engagementportion 211 of the head 21 of the screw member 21 that can be formed ofa series of barbs, teeth or protruding ribs is formed integral with theserrated inside retaining portion 11 of the cap 1. Thereafter, thespring member 4 is inserted into the center opening 10 of the cap 1 tosleeve the deformable coiled body 41, and then the barrel 3 is insertedinto the center opening 10 of the cap 1 to have the screw member 2 andthe spring member 4 be accommodated in the inside accommodation space 30and the two end portions 42 of the spring member 4 be respectivelystopped the bottom side of the head 21 of the screw member 2 and thestep 31 of the barrel 3. Further, the retainer ring 34 is fastened tothe periphery of the shank 22 of the screw member 2 and positioned inthe locating groove 32 inside the barrel 3.

Referring to FIG. 8, during application of the present invention tofasten a set of metal plate members 8, an automatic installation machineis used to pick up the plate member fastener and then to insert thebottom extension tube 33 of the barrel 3 of the plate member fastenerinto the mounting through hole 811 of the first metal plate member 81and to attach the bonding edge 331 of the barrel 3 to the solder paste812 that was applied to the border area of the mounting through hole 811of the first metal plate member 81, and then a reflow soldering processis applied to have the barrel 3 be bonded to the first metal plate 81.

After installation of the barrel 3 in the first metal plate member 81,attach the first metal plate member 81 to the second metal plate member82 to aim the screw member 2 at the screw hole 821 of the second metalplate member 82, and then force the cap 1 downwards and rotate the cap 1to drive the outer thread 231 of the screw member 2 into the screw hole821 of the second metal plate member 82, and then attach a hand tool(for example, screwdriver) to the tool groove 24 of the screw member 2and rotate the hand tool to tighten up the connection between the screwmember 2 and the second metal plate member 82. Thus, the first metalplate member 81 and the second metal plate member 82 are firmly securedtogether by the plate member fastener. By means of the effect of thestop end edge 2311, the invention avoids overthreading of the screwmember 2 and facilitates disconnection of the first metal plate member81 from the second metal plate member 82.

Further, the stop end edge 2311 of the screw member 2 is a flat edgeextending in direction perpendicular to the axis of the screw member 2.Thus, when the spring member 4 is received in the barrel 1 and the twoend portions 42 are respectively stopped at the bottom side of the head21 and stop end edge 2311 of the screw member 2, the screw member 2 willnot be forced to bias and can be accurately threaded into the screw hole821 of the second metal plate member 82.

While the present disclosure has been described with reference to oneexemplary embodiment, it will be understood that the description of theexemplary embodiment is not a limitation of the invention.

Although a particular embodiment of the invention has been described indetail for purposes of illustration, various modifications andenhancements may be made without departing from the spirit and scope ofthe invention. Accordingly, the invention is not to be limited except asby the appended claims.

1. A method for making a screw member for plate member fastener, themethod comprising the steps of: (a) Prepare a metal element subject to apredetermined size, and then process said metal element through a coldextrusion forging operation to form a head at one end, a connectionportion at an opposite end and a shank between said head and saidconnection portion. (b) Process said connection portion through a threadrolling operation to form threads around the periphery of saidconnection portion (c) Process said threads to form a stop end edge atone side in proximity to said shank. (d) Finish the final product. 2.The method of claim 1, wherein the step (a) is to put the prepared metalelement put in between an upper die and a bottom die of a forgingmachine for enabling the metal element to be forged to form the desiredshank and the desired connection portion, and then to attach a hammerforging die to one end of the metal element outside the upper die andthe bottom die and to hammer the hammer forging die in forging therespective end of the metal element into the desired head.
 3. The methodof claim 1, wherein the step (b) is to put the shape-formed metalelement thus obtained from the step (a) in between a thread rolling faceof a first flat thread rolling die of a first thread rolling die set ofa thread rolling machine and a thread rolling face of a second flatthread rolling die of said first thread rolling die set of said threadrolling machine, and then to reciprocate the first flat thread rollingdie and second flat thread rolling die of said first thread rolling dieset in reversed directions so as to form the desired threads around theperiphery of the connection portion.
 4. The method of claim 3, whereinthe step (c) is to put the semi-finished screw member thus obtained fromthe step (b) in between a first flat thread rolling die of a secondthread rolling die set of said thread rolling machine that has a threadrolling face at one side thereof and an end edge-forming face suspendingin the thread rolling face and a second flat thread rolling die of saidsecond thread rolling die set that has a thread rolling face at one sidethereof, and then to reciprocate the first flat thread rolling die andsecond flat thread rolling die of said second thread rolling die set inreversed directions in forcing the respective thread rolling facesagainst the connection portion of the semi-finished screw member andcausing said flat end edge-forming face to cut an end portion of onelast thread of the threads of the semi-finished screw member into thedesired stop end edge.